//裴波那契数列的递归实现
#include <iostream>
using namespace std;

int fib(int i)
{
    if (i < 2)
        return i == 0 ? 0 : 1;
    
    return fib(i - 1) + fib(i - 2);
    
}

int main(void)
{
    int a = fib(5);
    if (a)
    {
        cout << a << endl;
    }
    cout << "hello world" << endl;
    return 0;
}